Stabilized paraffin wax



Patented Apr. 24, 1951 STABILIZED PARAFFIN WAX Herman J; Zoeller, Union, N. J., assignor to Standard Oil Development Company, a corporation of Delaware No Drawing. Application March 7, 1947,

- Serial No. 733,187

2 Claims. (01. 106-270) This invention relates to a novel paraffin wax composition and particularly to a method of preventing the' development of objectionable color insuch material.

It is well known that paraflin Wax derived from certain crudes, particularly such crude oils as Panhandle crudes, Salt Flat crudes, or Reagan type crudes, tend to develop discoloration when subjected to heat or ultra-violet light. This is a highly undesirable property when the finished wax is to be usedfor various commercial purposes, andespecially when it is to be employed in the packaging of foods. It is an object of the present invention to provide a means for stabilizingsuch wax products against deterioration and discoloration.

t In accordance with this invention, refined parafiin waxes, which have been rendered white or colorless by the usual refining processes, are stabilized against the deteriorating effects of heat and light by incorporating therein a small proportion of a polymerized alkyl siloxane. Such dihydrocarbon silicones are considered to have the general structure. I

in which R and R are hydrocarbon radicals such as alkyl, cycloalkyl, aryl, aralkyl, or alkaryl radi-' cals, preferably having less than carbon atoms, and a: is a positive integer greater than 1.

Among the many radicals represented by R and R, special reference may be made to methyl; ethyl; normal and iso propyl; normal, iso, secondary and tertiary butyl; and the various amyl, hexyl, heptyl, octyl and homologous groups.

I against discoloration.

. Althoughthe most suitable degree of polymerization cannot be determined, it has been found that the best results will be obtained when the polysiloxane possesses physical properties within the following range:

Viscosity l;. 50-1000 centistokes at C. Freezing point Not greater than -50 C. Specific gravity 0968-1001 at 25 C.

Refractive index 1.4030-1.427 at 25 C. Flash point 530-640'F.

The amount of the polysiloxanes which are generally efiective in stabilizing wax compositions is from about 0.001% to 0.05%, based on the paraflin wax base. Quantities greater than about 0.05% will not readily dissolve in the wax and will tend to produce cloudiness.

The polysiloxanes may be incorporated in the melted wax at any time after completion of the refining process, preferably after the final filtration and before solidifying the same and packag- In the following example there is described a series of tests of the color stability of a refined wax containing varying quantities of a typical polysiloxane. It is to be understood that this example is given by way of illustration only and thereby.

Example A refined paraffin wax was prepared by the following method: A paraffin distillate fraction was dewaxed to obtain a slack wax containing about 30% oil. The slack wax'was then sweated to a crude scale wax, the latter treated with about 18 pounds of sulfuric acid of 104% concentration per gallons of wax at F. The spent acid and sludge were removed, and the acid-treated wax was neutralized, washed, sweated and filtered to produce a highly refined paraffin wax having a melting point of 132 F.

In the above-described wax were incorporated various quantities of a polydimethyl siloxane having the following properties:

The blends thus produced were submitted to color stability and heat stability tests, as well as toinspections of melting point, tensile strength and other properties, the results and types of tests being shown in the following table:

above, but is to be limited solely by the terms of the appended claims.

Blend Composition:

Refined Wax, Weight Per Cent 100 99. 99 99. 95 99. 9 99. 8 Siloxane Oil, Weight Per Cent. None 0.01 0.05 0.1 0.2

Inspections:

Melting Point, F 132 132 132 .1 132 132 Per Cent Oil-ASTM 0.6 0.5 0.6 0.6...- 0.6 Color, Saybolt +30 +30. +30... Cloudy Cloudy. Heat Stability: Color,

Saybolt 2536 2 +5 .+6 +3 +2 Light Stability: Color,

Saybolt 231R. 16 +12... +9 Tensile Strength,

Pounds/y; sq. in 53 54 50 45 -41 U. S. P. Acid Test Passed. Passed Passed Passed.. Passed.

1 Heat stability: The wax is maintained at 302 F. for 16 hours in-the presence of a copper strip and the color of the wax then determined.

2 Tag Robinson scale used, since value is below Saybolt color'scale range. A 3 Light Stability: A cake of wax V inch thick is exposed for 7 days to a Westmg house Sterilamp at room temperature and the color then determined.

In each of these stability tests a, final color of 0' Saybolt or higher is considered satisfactory.

The advantages. to be secured by incorporating a polysiloxane in refined waxes in accordance with the present invention are readily apparent by the decided improvement secured with respect to. color, which. may bereadily appreciated when Saybolt color and Tag Robinson color are correlated on. an absolute color scale as follows:

fii i Saybolt Tig Robin Scale Color son In the appended claims the expression paraffin Wax is intended to refer to a refined petroleum wax of the crystalline type as obtained from a parafiin distillate out, especially from parafiinic crude oils.

It is not intended that the invention be limited by any of the illustrations which are given I claim:

1. A refined colorless parafiin wax of a melting point of about 132 F. which has been treated with. concentrated sulfuric acid and has incorporated therein about 0.001 to about 0.05% of a polydimethyl siloxane having the following properties:

Viscosity 50-1000 centistokes at 25 C. Freezing point Not greater than 50- C. Specific gravity 0968-1001 at 25C. Refractive index. 140304.427 at 25 C.

Flash point 530640 F.

2. A refined colorless paraffin Wax of a melting point of about 132 F. which has been treated with concentrated sulfuric acid and has incorporated therein about 0.001 to about 0.05% of a polydimethyl siloxane having the following properties:

Viscosity 350 centistokes at 25 C. Freezing point 50 C.

Specific gravity 0.972 at 25 C. Refractive index 1.0432 at 25 C.

Flash point 625? F.

HERMAN J. ZOELLER.

REFERENCES CITED The. following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,383,521 Sowa Aug. 28, 1945 2,416,504 Trautman Feb. 25, 1947 

1. A REFINED COLORLESS PARAFFIN WAX OF A MELTING POINT OF ABOUT 132* F. WHICH HAS BEEN TREATED WITH CONCENTRATED SULFURIC ACID AND HAS INCORPORATED THEREIN ABOUT 0.001 TO ABOUT 0.05% OF A POLYDIMETHYL SILOXANE HAVING THE FOLLOWING PROP ERTIES: 